package network;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class TcpEchoServer {
    private ServerSocket serverSocket = null;
    public TcpEchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }
    public void start() throws IOException {
        ExecutorService executorService = Executors.newCachedThreadPool();
        System.out.println("服务器启动！");
        while(true){
            //和客户端建立链接
            Socket clientSocket = serverSocket.accept();
            //如果直接调用processConnection方法，该方法会影响这个循环的二次执行，导致accept（链接）不及时
            //床架新的线程，用新线程来调用processConnection
            //每次来一个新的客户端都会创建一个新的线程
//            Thread t = new Thread(()->{
//                try {
//                    processConnection(clientSocket);
//                } catch (IOException e) {
//                    e.printStackTrace();
//                }
//            });
//            t.start();
            executorService.submit(new Runnable(){

                @Override
                public void run() {
                    try {
                        processConnection(clientSocket);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            });

        }
    }
    //通过这个方法来处理一个链接
    private void processConnection(Socket clientSocket) throws IOException {
        System.out.printf("[%s:%d] 客户端上线！\n",clientSocket.getInetAddress().toString(),
                clientSocket.getPort());
        //try()这种写法，（）中允许写多个流对象，使用；来分割。
        try(InputStream inputStream = clientSocket.getInputStream();
            OutputStream outputStream = clientSocket.getOutputStream()){
            //使用scanner和printWriter将inputStream和outputStream进行包裹，这样可以将字符流转换为字节流
            Scanner scanner = new Scanner(inputStream);
            PrintWriter printWriter = new PrintWriter(outputStream);
            while(true){
                //1、读取请求
                if(!scanner.hasNext()){
                    //读取的流到了结尾了（对端关闭了）,打印客户端的IP地址和端口号
                    System.out.printf("[%s:%d] 客户端下线！\n",clientSocket.getInetAddress().toString(),
                            clientSocket.getPort());
                    break;
                }
                //直接使用scanner读取一段字符串
                String request = scanner.next();
                //2、根据请求计算响应
                String response = process(request);
                //3、把响应返回给客户端.不要忘记，响应这里也要带上换行的
                printWriter.write(response+"\n");
                printWriter.flush();
                System.out.printf("[%s:%d] req: %s; resp: %s\n",clientSocket.getInetAddress().toString(),
                        clientSocket.getPort(),request,response);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            clientSocket.close();
        }
    }

    public String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer tcpEchoServer = new TcpEchoServer(9090);
        tcpEchoServer.start();
    }
}
